The present invention relates to the field of thermal management of semiconductor devices; more specifically, it relates to a technique of reusable redundant circuitry to prevent overheating of semiconductor devices.
Semiconductor devices, especially microprocessor and other fast logic circuits, dissipate large amounts of heat during operation. Thermal management of such devices has been traditionally managed using heat sinks or other related thermal transfer solutions. A different class of solutions attacks the problem from within the chip itself.
Turning to the prior art, U.S. Pat. No 5,206,778 to Flynn et. al., teaches an on chip temperature sensing circuit that may be used by a thermal management system that may shut down some chip circuits. This patent is hereby incorporated by reference.
U.S. Pat. No. 5,451,892 to Baily, describes a thermal sensor circuit that controls the frequency of the CPU clock in a microprocessor in response to an increase in temperature above a first limit, and return to normal frequency in response to a decrease below a second limit. Though the chip is kept from overheating, for significant periods of time the chip is operating at lower speeds which would be a disadvantage in many situations.
Following along the same lines, U.S. Pat. No. 5,590,061 to Hollowell et. al. teaches turning off a portion of the chip in response to an increase in temperature above a first point and turning it back on in response to a decrease in temperature. Though the chip is kept from overheating, for significant periods of time portions of the chip are not operating which would be a disadvantage in many situations.
The present invention provides an on chip thermal management system that does not have significant impacts to the performance of the chip.
The present invention includes redundant chip sections held in standby that may be substituted for chip sections that are at risk of over heating based on certain sensor signals. When these signals are received operations of the chip section at risk transferred to a redundant chip section and the chip section at risk is shut down. After the original chip section has cooled, it becomes available as a replacement chip section itself. Therefore it is an object of the present invention to provide a semiconductor device with reusable redundant chip sections switchable among themselves.
Three methods of controlling the heat using different sensor signals are taught. According to the first method temperature sensing is used to activate and deactivate chip sections on as needed basis. In the second method a simple interval timer is used to sequentially activate and deactivate the various chip sections and in the third method, a transaction counter is used to count the number or rate of transactions within a section and to activate and deactivate chip sections on a as needed need basis. Accordingly, it is another object of the present invention to provide switching of chip sections to be based on temperature sensing, interval timing or transaction counting.
It is a still further object of the invention to provide a multi-chip application which includes identical redundant chips held in standby that may be substituted for chips that are at risk of over heating based on temperature sensing, interval timing, or transaction counting.